Amid the government’s injustice and class bias, people want to see their deep anger reflected by opposition politicians

The season of the Big Speech approaches. They may pretend to be on holiday but first, second and third drafts of party conference speeches are already covered in corrections, swerving changes of direction, question marks and deletions as the leaders sit on beaches dandling their children, pretending to relax.

But Kinnock’s speeches also stand as a marker that great oratory may not win elections. He was, after all, defeated by John Major, the most cliche-prone prime minister with the smallest vocabulary and flattest intonation of any in my political lifetime: his comical “cones hotline” party conference speech stands as the exemplar. Perhaps only Iain Duncan Smith’s frog-throated “Do not underestimate the determination of the quiet man” conference speech was more disastrous, from a man you would still struggle to underestimate.

At the Edinburgh festival this year in a small venue was a radiant one-man performance – BigMouth, written and performed by Valentijn Dhaenens from the Netherlands. Gathering up great and infamous political speeches, his juxtapositions compare and contrast passions and perfidies with subtlety and wit, ranging across the French, Flemish, American and German tongues. Reaching back down 2,500 years of oratory, from Socrates on his deathbed to America’s modern Tea Party, he spins the power and infamy of public words like plates on a stick. He starts, appropriately enough, by singing an Agnus Dei, his only reminder that religions always were the pastmasters in playing on the strings of the vulnerable human heart.

The centrepiece of his tour de force is a juxtaposition of a blood-curdling speech by General Patton interleaved by Goebbels’ words, forwards and backwards between the two, each firing up their forces for bloody sacrifice in the second world war. Goebbels is delivered with sinister quietism, exhorting the exhausted citizens of 1945 to summon up their last energies, for “total war is the demand of the hour … Now people rise up and let the storm break loose!”. Forget the sanitised movie version of Patton’s speech to the 3rd army, here it’s an unexpurgated “Rip up their belly, shoot them in the guts”. In wartime, extreme rhetoric is an essential fighting weapon – from Henry V to Churchill.

But in peace, matching the tone to the temper of the times is everything. Is it coincidence that so many great political rhetoricians came to a bloody end? Passionate words risk stirring disproportionate deeds. Both Kennedy brothers, Martin Luther King and Malcolm X were killed for their words. Patrice Lumumba’s triumphant 1960 speech on winning independence after 80 years of colonial tyranny in Belgian Congo (now the Democratic Republic of the Congo) predicted great glories ahead, but it brings tears to the eyes knowing what came a year later – deposition, execution and long civil wars. Maybe the contamination of everyday politics means the only practitioners who leave heroic memories die young.

In among the rousing and the terrifying are the mumbling, bumbling and the odd: George W Bush descends into absurd rubbish when he loses the teleprompter; King Baudouin makes a curious abdication speech after refusing to sign an abortion act; Ronald Reagan proclaims he’d rather his little girls die now believing in God than live to grow up atheists under communism. Does any of this offer easy guidance to our leaders? Great speeches spring from times of heightened national drama. In democracies we make ambivalent demands on our leaders, rightly suspicious of any overreaching rhetoric yet demanding to be moved and impressed nonetheless.

Compared with the relatively calm postwar era of British history, these times may rank as a moment that calls for a heightening of political language. My postwar generation has never known such a long and deep recession, never seen a government impose such austerity, never watched a chancellor deliberately depress growth through unshakeable, evidence-denying dogma. We have never watched the incomes of the bottom half of society assaulted while the upper echelons stay unscathed. We have never witnessed the effrontery of a chancellor claiming “We’re all in this together”, then piling the sacrifice on to the most hard-pressed while cutting tax for rich.

The challenge for Ed Miliband is how to capture the right tone of indignation at this injustice and class bias, how witheringly to crush the wilful ignorance of Tory backbenchers calling the British “the worst idlers” when so many desperately seek more work.

Travelling around Britain this summer I found wells of anger in people who don’t see it reflected in overcautious Labour at Westminster. Worse is to come, with 80% of cuts not yet implemented, housing benefit evictions and disability scooter repossessions not publicly visible. Good rhetoric catches the spirit of the times, not extreme but forensic, resonant with what’s happening – the million young people without jobs, the rising debt wasted on unemployment instead of constructive investment. This peacetime crisis needs a lick of warlike fire.